Field of the Invention
The present invention relates to an image capturing apparatus configured to detect an object, a control method of the image capturing apparatus, and a non-transitory computer-readable medium.
Description of Related Art
In recent years, many image capturing apparatuses that detect an object such as a person present in a shooting target field and perform focus adjustment of an image pickup lens with respect to the object have been put on the market.
Generally, detection of an object is performed on the basis of information from an image sensor constituted by, for example, a complementary metal oxide semiconductor (CMOS) or a charge coupled device (CCD). However, in recent years, a single-lens reflex (SLR) camera that employs an image sensor constituted by a CMOS, a CCD, or the like as a photometric sensor for measuring the luminance of the shooting target field has been put on the market, and this single-lens reflex camera not only measures the luminance but also detects a human face and the like. Focus adjustment of the image pickup lens can be automatically performed with respect to the object by transmitting information about the detection result to a known focus detection unit employing a phase difference detection method.
However, from the viewpoint of the size or cost of the camera, it is difficult to impart a photometric optical element (photometric lens) for forming an image on the photometric sensor with an image forming performance in which chromatic aberration and other like aberrations are sufficiently suppressed.
Therefore, in the case of detecting an object by using a photometric optical element and a photometric sensor, it is sometimes difficult to achieve a high image forming performance, and thus a way to improve the performance of object detection is sought.
Japanese Patent Laid-Open No. 2012-34130 discloses an example in which, in order to suppress deterioration of image quality due to a change in temperature of an optical system, an image processing circuit preemptively converts a change in an image forming state of the optical system occurring due to a change in temperature into weights Wr, Wg, and Wb for respective primary color signals of R, G, and B and stores these weights for image processing. In this known technique to suppress deterioration of image quality due to a change in temperature of an optical system, the weights Wr, Wg, and Wb are set in response to an output from a temperature measuring element, and the respective primary color signals of R, G, and B are combined by using the weights to generate a signal in which an effect of aberration is suppressed.
The above-described technique only takes into consideration the change in the image forming state of the optical system occurring due to the change in temperature. However, aberration that may cause the deterioration of resolution actually occurs also due to a field curvature, astigmatism, and other like parameters, and the aberration occurring due to these additional factors also has to be suppressed.